A color image forming apparatus includes: a multiple number of process printing units, each having a photoreceptor drum for forming a toner image with a toner corresponding to color-separated image information for each color and a developing unit for supplying the toner to the surface of the photoreceptor drum, wherein the toner images formed by electrophtography on the surfaces of the photoreceptor drums are transferred to a recording medium by the function of a transfer electric field, and is characterized in that the toners to be supplied to the photoreceptor drums from the developing units for every color are specified so that the time constants .tau. of the toners become greater as the position of toner supply is located more upstream in the development process.